1. Field of the Invention
The present invention generally relates to a method of checking communication-path data in an MPLS (multi protocol label switching) communication scheme, and relates to a router a switch, and a communication system operating based on such a method. The present invention particularly relates to a method of checking communication-path data in an MPLS communication scheme for the purpose of checking integrity of label data controlled by a MPLS router and switch data controlled by a trunk switch, and relates to a router, a switch, and a communication system operating based on such a method.
2. Description of the Related Art
In the MPLS communication system that uses ATM (asynchronous transfer mode) switches as trunk switches, data for communication control purposes are maintained as label data controlled by an MPLS router and switch data controlled by an ATM switch.
FIG. 1 is an illustrative drawing showing a system based on the MPLS communication scheme.
An MPLS router 11 converts an IP packet 12 into an ATM cell 21 when the IP packet 12 is supplied from an IP (internet protocol) network 10, and supplies the ATM cell 21 to an ATM network 20. The ATM cell 21 is transferred to an MPLS router 31 via ATM switches 22 and 24 and the like through ATM switching based on PVC (permanent virtual circuit).
The MPLS, router 31 extracts an IP packet 32 from an ATM cell 25 supplied from the ATM network 20, and supplies the IP packet 32 to an IP network 30.
The MPLS communication scheme will be described further in detail in the following.
FIG. 2 is an illustrative drawing for explaining a principle of the MPLS communication system.
In FIG. 2, an MPLS router 40 is provided with label data 41, which indicates correspondences between destination IP addresses and VPI/VCI (virtual path identifier/virtual channel identifier). An ATM switch 50 is provided with switch data 51 that is used for ATM switching.
The MPLS router 40 converts IP packets 42 and 43 supplied from the IP network into ATM cells 44 and 45 by utilizing the label data 41, and supplies the ATM cells 44 and 45 to the ATM switch 50. For example, when the IP packet 42 is supplied, the MPLS router 40 refers to a destination IP address xe2x80x9c164.69.15.2xe2x80x9d of the IP header, and reads VPI/VCI xe2x80x9c1/10xe2x80x9d from the label data 41 that corresponds to this destination IP address. Then, the MPLS router 40 generates the ATM cell 44 by using the obtained VPI/VCI and the IP packet 42.
The ATM switch 50 performs ATM switching on the ATM cells 44 and 45 supplied from the MPLS router 40 where the switch data 51 is used for such ATM switching. By switching, the ATM switch 50 transfers the ATM-cells 44 and 45 to an MPLS router 60 or an MPLS router 61. For example, when the ATM cell 44 is supplied, the ATM switch 50 refers to the VPI/VCI xe2x80x9c1/10xe2x80x9d, and reads VPI/VCI xe2x80x9c2/15xe2x80x9d and an output-communication-line number 1 from the switch data 51 as they correspond to the VPI/VCI xe2x80x9c1/10xe2x80x9d. Then, the ATM switch 50 generates an ATM cell 52 by utilizing the obtained VPI/VCI, and outputs the ATM cell 52 to the communication line of the output-communication-line number 1.
The MPLS router 60 extracts an IP packet 62 from the ATM cell 52 supplied from the ATM switch 50, and outputs the IP packet 62 to an IP network.
In this manner, data necessary for communication control in the MPLS communication scheme are kept in storage as the label data 41 controlled by the MPLS router and the switch data 51 controlled by the trunk switch.
When there is a need to identify a fault point during a setup of communication or upon detection of communication fault, the label data 41 and the switch data 51 have to be checked as to their contents. Further, in such a situation, the ATM communication lines need to be monitored to check whether the MPLS router 40 is operating normally to perform ATM-cell conversion as well as to check whether the ATM switch is receiving ATM cells without trouble.
In order to check the label data controlled by the MPLS router and the switch data controlled by the trunk switch, a visual inspection of the data is necessary. When the MPLS router and the trunk switch are located at physically distanced places or maintained by different administrators, such a visual inspection may be difficult.
Namely, in such cases, a check on the label data and the switch data cannot be made promptly, thereby making it difficult to promptly identify a fault point.
Further, apart from monitoring the communication lines, there is no other way of checking whether the MPLS router is correctly converting protocol data for the trunk switch and checking whether the protocol data converted by the MPLS router is correctly supplied to the trunk switch.
Accordingly, there is a need for a method for checking communication-path data in the MPLS communication system where the method can help to identify a fault point promptly and easily and help to make a prompt recovery.
It is a general object of the present invention to provide a method for checking communication-path data that substantially obviates one or more of the problems caused by the limitations and disadvantages of the related art.
Features and advantages of the present invention will be set forth in the description which follows, and in part will become apparent from the description and the accompanying drawings, or may be learned by practice of the invention according to the teachings provided in the description. Objects as well as other features and advantages of the present invention will be realized and attained by a method, a router, and a switch particularly pointed out in the specification in such full, clear, concise, and exact terms as to enable a person having ordinary skill in the art to practice the invention.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a method of checking communication-path data in a system in which a router connecting first and second networks operating on different protocols is connected to a switch of the second network. The method includes the steps of changing the router and the switch from a normal mode to a test mode, checking consistency between router communication-path data controlled by the router and switch communication-path data controlled by the switch by sending the router communication-path data to the switch during the test mode, and checking communication between the router and the switch by sending cells from the router to the switch and returning the cells from the switch to the router during the test mode.
In the method described above, the communication-path data controlled by the router and the communication-path data controlled by the switch are checked as to whether they are consistent with each other, and cells transmitted from the router to the switch are returned from the switch to the router so as to allow a check to be made as to communication between the router and the switch, so that a consistency check of the communication-path data, a cell-transparency check, and a connection check between the router and the switch can be easily made.
Accordingly, the method of checking communication-path data according to the present invention can help to identify a fault point easily and promptly in the communication system. In other words, when the communication system suffers a fault, it is possible to decide which one of the trunk switch and the router is suffering the fault, thereby separating the fault point from the rest of the system.
According to another aspect of the present invention, test signals are used for reporting results of the consistency check and results of the communication check. Therefore, the check results can be promptly and easily collected, which allows a fault point to be readily identified in a short time period.